1. FIELD OF THE INVENTION
The present invention generally relates to a compact-type gas-insulated switchgear apparatus, or more in particular to a compact-type gas-insulated switchgear apparatus with a compact cable head casing easily connectable with other electrical equipments.
2. DESCRIPTION OF THE PRIOR ART
In conventional compact-type gas-insulated switchgear apparatuses, as disclosed in JP-A-60-187213, openings connectable with circuit breaker terminals are formed in different directions at the ends of a circuit breaker casing, and one of the openings is connected to a main bus, with the other opening to a cable head terminal device. This terminal device has a disconnector and a ground switch in the cable head casing. A selected one of the disconnector and the ground switch is equipped with a moving element (needle) switchable in the direction perpendicular to the axis of the cable head casing, and the other has a moving element switchable in the direction parallel to the axis of the cable head casing.
In the above-described compact-type gas-insulated switchgear apparatus comprising a disconnector and a ground switch incorporated in a casing containing a cable head, the configuration of the disconnector and the ground switch described above makes it difficult to form a connector opening to the cable head casing for connecting other power equipment such as a lightning device. If the lightning device is to be connected, it is necessary to replace with a cable head casing large in axial length to form a connector opening corresponding to the increase in axial length. Another method may be to incorporate the lightning device integrally in the cable head casing. According to this method, however, the diameter of the cable head casing undesirably increases, in any of the these configurations, the units of the switchgear apparatus of this type are connected to other electrically equipment differently depending on whether they are connected to a transformer or a transmission line. Therefore, common components have preferably a standard configuration regardless of the connecting conditions so as to be connectable with other electrical equipments according to particular conditions.